Great Salt Lake Purple-Sulfur Bacteria

A limnology student samples the purple-sulfur bacteria in the Great Salt Lake with a Schindler-Patalas plankton trap. These vividly colored photosynthetic bacteria live at a depth of approximately 7 m (24 feet) at the interface between an extremely salty deep-brine layer (25% salt), and the overlying water that is also salty (5-16%). The red pigments of these photosynthetic bacteria allow them to capture the small amount of light that is present deep in the lake. The normal green phytoplankton in the surface layer of the lake can be seen in the background.

"Limnology" is the study of inland waters

Photo: April 1987 after record freshwater inflows in previous years diluted the lake. Surface water salinity 6%.